Ultrastructural and Molecular Development of the Myotendinous Junction Triggered by Stretching Prior to Resistance Exercise.

The myotendinous junction (MTJ) is a highly specialized region of the locomotor apparatus. Here, we investigated the ultrastructural and molecular effects in the MTJ region after static stretching prior to the ladder-based resistance training. Thirty-two male, 60-day old Wistar rats were divided into four groups: Sedentary, Resistance Training, Stretching, and Stretching-Resistance Training. The gastrocnemius muscle was processed for transmission electron microscopy techniques and Western blot assay. We observed that the static stretching prior to the ladder-based resistance training increased the MTJ components, the fibroblast growth factor (FGF)-2 and FGF-6 protein expression. Also, we demonstrated the lower transforming growth factor expression and no difference in the lysyl oxidase expression after combined training. The MTJ alterations in response to combined training demonstrate adaptive mechanisms which can be used for the prescription or development of methods to reduce or prevent injuries in humans and promote the myotendinous interface benefit.

Structural and Ultrastructural Changes in the Tongue of mdx Mice.

The mdx mouse is an experimental model of Duchenne muscular dystrophy, a genetic disorder characterized by progressive muscular degeneration which affects the oral cavity musculature, and promotes difficulty in swallowing. This study aimed to describe morphological, structural, and ultrastructural changes in the tongue mucosa and musculature of mdx mice. Forty six-month-old mice were divided into two groups: Control C57bl/10 (n = 20) and mdx C57bl/10mdx (n = 20). The tongue was dissected and analyzed with light microscopy, scanning electron microscopy, and transmission electron microscopy techniques. Our results showed conical and triangular filiform, fungiform, foliate, and vallate papillae, and their connective tissue cores. The epithelium layers identified were corneum, granulosum, spinosum, and basale. The mdx group had a thicker epithelium. Lamina propria was composed of reddish and greenish collagen. In mdx, collagen was present in the musculature of the tongue's body and in the muscular tissue between mucous and serous glands of the caudal region. Musculature was also characterized by a shorter length of sarcoplasmic invaginations, myocytolysis in mitochondrial groupings, and inflammatory focus. In conclusion, the tongue of 6-month-old mdx mice had morphology, structure, and ultrastructure revealed, showing higher wear of filiform papillae indirect reflex from the muscular degeneration process.

Morphological Changes in the Motor Endplate and in the Belly Muscle Induced by Previous Static Stretching to the Climbing Protocol.

Static stretching provides benefits to the range of motion, modulates intramuscular connective tissue, and is incorporated into warm-up exercises. In this study, we present the effects in the motor endplate and belly muscle resulting from previous static stretching to climbing training. Twenty-four adult male Wistar rats were divided into four groups (n = 6 each): Sedentary (Sed), Climbing (Clb), Static stretching (Ss), and Static stretching prior to climbing (Ssc). The animals (Clb, Ss, and Ssc groups) were subjected to a training protocol 3×/week for 8 weeks, and the Ssc group was subjected to the Ss and Clb protocols in the same session. Samples from the animals were processed for immunostaining, histochemistry, and light microscopy. The Clb group presented a higher motor endplate; the Ss group presented no changes in the motor endplate; and the Ssc group demonstrated a higher compactness. We concluded that static stretching prior to the climbing protocol maintained the density of the motor endplate and increased the compactness of the neuromuscular junction structure. Also, there was a reduction in the myofibers' diameter (Type I and IIa), an increase in myofibrillar densities (Type I and IIx, and total), and the reorganization of the myonuclei and the interstitium.

Structural and ultrastructural characterization of the palatine epithelium of the Guinea pig: A new record of telocytes in the oral cavity.

The morphology of the oral cavity of mammals relates to diet, habitat, and function. The palate is an important region with adaptations for oral somatosensation and mechanical loads due to the pressure of the tongue with food. The research aimed to describe the structural and ultrastructural characteristics of the epithelium and the connective tissue cores of the guinea pig palate using macroscopic, light microscopy, scanning electron microscopy, and transmission electron microscopy analysis. The hard palate had conical and filiform papillae, and the soft palate had open salivary ducts. After the removal of the epithelium, the connective tissue cores revealed thin filaments and laminar projections in the hard palate, and opening ducts were evidenced in the soft palate. The palatine epithelium was keratinized and organized by layers, lamellated corpuscles were found in lamina propria of the hard palate. In contrast, the soft palate had glands clusters associated with nerve fibers, and in both regions were identified telocytes. We concluded that the hard palate presented conical and filiform papillae that differ from other mammals. Besides, it is a new description of the connective tissue cores morphology and the first record of the telocytes in this anatomical region for mammals.